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flood-frequency relation for each station was determined by statistically combining the relations developed from the recorded and the synthetic data. Flood- frequency results were then regionalized using both a multiple-regression method and a station-year method. Lastly, a dimensionless hydrograph technique was tested to determine if estimated flood characteristics could be used to develop a reliable synthetic hydrograph. The principal conclusions of this preliminary analysis are: 1. The results of the multiple-regression and station-year methods were found to be in close agreement; depending on drainage area size, the station-year results were 9 to 23 percent lower for the 100-year peak discharge. The regression results should be used to provide the regional estimates of flood characteristics at ungag- ed basins. 2. The magnitude and frequency of floods can be estimated from the effective drainage area with a standard error of estimate of 30 to 50 percent. The relations are generally applicable to basins rang- ing in size from about 0.5 to 15 mi', but separate equations for basins less than and greater than 3 mi' were found to give better results. 3. For any peak discharge less than about 13,000 ft3/s, flood volume can be estimated with a standard error of estimate of about 62 percent. 4. Using estimated peak discharge and flood volume, a method devel- oped by Craig (1970) provides synthetic flood hydrographs with shapes very similar to the flood hydrographs observed in this study. 5. The flood-frequency and flood-volume relations reported are only applicable to rural basins with natural-flow conditions. However, urbanization resulting in less than 30 percent effective impervious area may not significantly affect these flood characteristics. SELECTED REFERENCES Bailey, J. F., and Ray. H. A., 1966, Definition of stage-discharge relation in natural channels by step-backwater analysis: U.S. Geological Survey Water- Supply Paper 1869-A, 21 p. Benson, M. A., 1962, Evolution of methods for evaluating the occurrence of floods: U.S. Geological Survey Water-Supply Paper 1580-A, 30 p. Benson, M. A. and Carter, R. W., 1973, A national study of the streamflow data-collection program: U.S. Geological Survey Water-Supply Paper 2028, 44 p. Bodhaine, G. L., 1968, Measurement of peak discharge at culverts by indirect methods: U.S. Geological Survey Techniques of Water-Resources Investiga- tions, Book 3, Chapter A3, 60 p. Chow, V. T., ed., 1964, Handbook of applied hydrology, a compendium of water- resources technology: New York, McGraw-Hili Book Co., sec. 7, p. 47-48. 30